Background. Insulin sensitivity and insulin secretion are traits that are both genetically and environmentally determined.Aim. The aim of this study was to describe the distribution of the insulin sensitivity index (Si), the acute insulin response, and glucose effectiveness (Sg) in young healthy Caucasians and to estimate the relative impact of anthropometric and environmental determinants on these variables.Methods. The material included 380 unrelated Caucasian subjects (18-32 yr) with measurement of Si, Sg and insulin secretion during a combined intravenous glucose (0.3 grams/kg body weight) and tolbutamide (3 mg/kg body weight) tolerance test.Results. The distributions of Si and acute insulin response were skewed to the right, whereas the distribution of Sg was Gaussian distributed. Sg was 15% higher in women compared with men ( P Ͻ 0.001). Waist circumference, body mass index, maximal aerobic capacity, and women's use of oral contraceptives were the most important determinants of Si. Approximately one-third of the variation of Si could be explained by these factors. Compared with individuals in the upper four-fifths of the distribution of Si, subjects with Si in the lowest fifth had higher waist circumference, higher blood pressure, lower VO 2 max, and lower glucose tolerance and fasting dyslipidemia and dysfibrinolysis. Only 10% of the variation in acute insulin response could be explained by measured determinants. Conclusion. Estimates of body fat

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SF %BF showed the highest correlation and best agreement with DXA %BF in identifying children with excess fat (+1 s.d.).

Serum levels of total and free testosterone and 17 beta-estradiol were determined in 144 men with acute ischemic stroke and 47 healthy male control subjects. Blood samples from patients were drawn a mean of 3 days after stroke onset and also 6 months after admission in a subgroup of 45 patients. Initial stroke severity was assessed on the Scandinavian Stroke Scale and infarct size by computed tomographic scan. Mean total serum testosterone was 13.8 +/- 0.5 nmol/L in stroke patients and 16.5 +/- 0.7 nmol/L in control subjects (P = .002); the respective values for free serum testosterone were 40.8 +/- 1.3 and 51.0 +/- 2.2 pmol/L (P = .0001). Both total and free testosterone were significantly inversely associated with stroke severity and 6-month mortality, and total testosterone was significantly inversely associated with infarct size. The differences in total and free testosterone levels between patients and control subjects could not be explained by 10 putative risk factors for stroke, including age, blood pressure, diabetes, ischemic heart disease, smoking, and atrial fibrillation. Total and free testosterone levels tended to normalize 6 months after the stroke. There was no difference between patients and control subjects in serum 17 beta-estradiol levels. These results support the idea that testosterone affects the pathogenesis of ischemic stroke in men.